JOHANNESBURG - South African relief group Gift of the Givers, which is negotiating with al-Qaeda affiliates for the release of a Bloemfontein teacher in Yemen, has appealed to the terrorist group to free him as he is already an ill man.

Pierre Korkie and his wife Yolande were captured in May 2013 in the Yemeni city of Taiz.

Gift of the Givers successfully negotiated Yolande's release without any ransom being paid, but the militants have now demanded R32 million within the next 24 hours or the 53-year-old will face execution.

Yolande says her husband will require immediate medical attention if he is released.

Yolande Korkie attends a press conference in Johannesburg after being held captive in Yemen on 16 January 2014. Picture: Govan Whittles/EWN

"Pierre has a hernia in his groin and the renal system is now bulging out on the one side and the other side has fallen to the inside."

Gift of the Givers founder, Imtiaz Sooliman, has been facilitating negotiations and says it makes sense for the militants to free Pierre as he is of no value to them.

Yolande Korkie with Gift of the Givers' Dr Imtiaz Sooliman during a press conference in Johannesburg on 16 January 2014. Picture: Govan Whittles/EWN

"This is an old man, he is ill and you said you captured the wrong people. Why don't you just let him go?"

They have until Saturday to raise the funds for the ransom and it's still unclear whether al-Qaeda will consider their international plea for a stay of execution.